UNIVERSITY    OF   CALIFORNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


THE   LATE   BLIGHT  OF  CELERY 


By  STANLEY  S.   ROGERS 


BULLETIN  No.  208 

(Berkeley,  Cal.,  January,  1911) 


BERKELEY 

THE   UNIVERSITY   PRESS 
1911 


Benj.   Ide  Wheeler,   Ph.D.,   L.L.D.,   President  of  the  University. 

EXPERIMENT   STATION   STAFF. 

E.  J.  WlCKSON,  M.A.,  Director  and  Horticulturist. 

E.   W.  Hilgard,  Ph.D.,   LL.D.,   Chemist    (Emeritus). 

W.  A.   Setchell,  Ph.D.,   Botanist. 

Elwood  Mead,  M.S.,   C.E.,   Irrigation  Engineer.      (Absent  on  leave.) 

Lerov  Anderson,  Ph.D.,  Dairy  Industry  and  Superintendent  University  Farm  Schools. 

Si.   E.  Jaffa,  M.S.,  Nutrition  Expert,  in  charge  of  the  Poultry  Station. 

R.  H.  Loughridge,  Ph.D.,   Soil  Chemist  and  Physicist    (Emeritus). 

C.   W.  Woodworth,  M.S.,   Entomologist. 

Ralph  E.  Smith,  B.S.,  Plant  Pathologist  and  Superintendent  of  Southern  California  Patho- 
logical Laboratory  and  Experiment  Station. 

G.  W.  Shaw,  M.A.,  Ph.D.,  Experimental  Agronomist  and  Agricultural  Technologist,  in  charge 
of  Cereal  Stations. 

E.  W.  Major,  B.Agr.,  Animal  Industry,  Farm  Manager,   University  Farm,   Davis. 

F.  T.  Bioletti,  B.S.,  Viticulturist. 

George  E.  Colby,  M.S.,  Chemist   (Fruits,  Waters  and  Insecticides),  in  charge  of  Chem.  Lab. 

H.  J.  Quayle,  A.B.,   Assistant  Entomologist,   Plant  Disease  Laboratory,   Whittier. 

W.  T.  Clarke,  B.S.,  Assistant  Horticulturist  and  Superintendent  of  University  Extension  in 

Agriculture. 
H.  M.  Hall,  Ph.D.,  Assistant  Botanist. 

C.  M.  Haring,  D.V.M.,  Assistant  Veterinarian  and  Bacteriologist. 
John   S.   Burd,   B.S.,   Chemist,   in  charge  of  Fertilizer  Control. 
E.   B.  Babcock,   B.S.,  Assistant  Agricultural  Education. 
H.  A.  Hopper,  M.S. A.,  Dairy  Industry,   University  Farm,  Davis. 
W.  B.  Herms,  M.A.,  Assistant  Entomologist. 

J.  H.  Norton,  M.S.,  Assistant  Chemist,  in  charge  of  Citrus  Experiment  Station,  Riverside. 
W.  T.  Horne,  B.S.,  Assistant  Plant  Pathologist. 

J.   E.   Coit,  Ph.D.,   Assistant  Pomologist,   Plant  Disease  Laboratory,   Whittier. 
C.  B.  Lipman,  Ph.D.,  Assistant  in  Soil  Bacteriology. 
R.  E.  Mansell,  Assistant  in  Horticulture,  in  charge  of  Central  Station  grounds. 

A.  J.   Gaumnitz,  M.S.,  Assistant  in  Cereal  Investigations,   University  Farm,   Davis. 

E.  H.  Hagemann,  Assistant  in  Dairying,  Davis. 

B.  S.  Brown,  B.S.A.,  Assistant  in  Horticulture,  University  Farm,  Davis. 

F.  D.  Hawk,  B.S.A.,  Assistant  in  Animal  Industry. 

J.  I.  Thompson,  B.S.,  Assistant  in  Animal  Industry,  Davis. 

R.  M.  Roberts,  B.S.A.,  Field  Assistant  in  Viticulture,  University  Farm,  Davis. 

J.  C.   Bridwell,  B.S.,  Assistant  Entomologist. 

C.  H.  McCharles,   B.S.,  Assistant  in  Agricultural  Chemical  Laboratory. 
J.  C.  Roper,  Patron  University  Forestry  Station,  Chico. 

Mrs.  D.  L.  Bunnell,  Secretary  to  the  Director. 
E.  C.  Miller,  Foreman  University  Forestry  Station,   Chico. 
N.  D.  Ingham,  B.S.,  Assistant  in  Sylviculture,   Santa  Monica. 
John  T.  Bearss,  Foreman  Kearney  Park  Station,  Fresno. 

E.  H.  Smith,  M.S.,  Assistant  Plant  Pathologist. 
T.  F.  Hunt,  B.S.,  Assistant  Plant  Pathologist. 

C.  O.  Smith,  M.S.,  Assistant  Plant  Pathologist,   Plant  Disease  Laboratory,   Whittier. 
M.  E.  Stover,  B.S.,  Assistant  in  Agricultural  Chemical  Laboratory. 
P.  L.  McCreary,  B.S.,  Laboratory  Assistant  in  Fertilizer  Control. 

F.  L.  Yeaw,  B.S.,  Assistant  Plant  Pathologist,  Vacaville. 
F.  E.  Johnson,  B.L.,  M.S.,  Assistant  in  Soil  Laboratory. 
Charles  Fuchs,  Curator  Entomological  Museum. 

P.  L.  Hibbard,  B.S.,  Assistant  Fertilizer  Control  Laboratory. 

W.  H.  Volck,  Field  Assistant  in  Entomology,  Watsonville. 

E.  L.  Morris,  B.S.,  Field  Assistant  in  Entomology,  San  Jose. 

J.  S.  Hunter,  Field  Assistant  in  Entomology,   San  Mateo. 

L.  M.  Davis,  B.S.,  Assistant  in  Dairy  Husbandry,  University  Farm,  Davis. 

L.  Bonnet,  Assistant  in  Viticulture. 

S.  S.  Ro<;krs,  B.S.,  Assistant  Plant  Pathologist,  Plant  Disease  Laboratory,  Whittier. 

B.  A.  Madson,  B.S.A.,  Assistant  in  Cereal  Laboratory. 

Waltkr  E.  Packard,  M.S.,  Field  Assistant  Imperial  Valley  Investigation,   El  Centre 

E.  E.  THOMAS,   B.S.,  Assistant  Chemist,  Plant  Disease  Laboratory,  Whittier. 


THE  LATE  BLIGHT  OF  CELERY 

By  STANLEY   S.    ROGERS 


SUMMARY. 

I1  "  In  the  peat  lands  of  Orange  Connty,  located  between  Santa 
Ana  and  the  Coast,  in  the  vicinity  of  Smeltzer,  a  very  large  celery 
growing  industry  has  developed,  the  crop  being  grown  particularly 
for  shipment  during  the  winter  after  the  eastern  celery  has  had  its 
season.  During  the  summer  of  1907  nearly  six  thousand  acres  of 
celery  were  planted  in  this  district.  Great  losses  in  the  crop  were  ex- 
perienced in  the  winter  of  1908  from  a  fungus  disease  causing  a  blight 
of  the  leaves  of  the  celery  plant  and  heavy  decay  during  shipment. 
The  fungus  responsible  for  this  disease  is  Septoria  petroselini  var.  apii. 
These  losses  were  estimated  as  causing  a  shrinkage  of  1950  car  loads  in 
shipment,  and  had  a  most  disastrous  effect  upon  the  quality  of  the 
celery  on  arrival  in  the  eastern  markets  and  the  financial  returns  from 
the  crop.  The  whole  money  loss  for  the  season  caused  by  this  fungus 
disease  was  conservatively  estimated  at  $550,000.00." 

2.  The  celery  blight  is  one  of  the  many  fungus  diseases  which  may 
be  controlled  by  spraying  with  Bordeaux  mixture. 

3.  While  a  great  deal  of  spraying  was  done  in  the  season  of  1908, 
the  results  were  not  uniformly  satisfactory ;  failures  in  controlling  the 
disease  being  chargeable  to  many  different  causes. 

4.  The  efforts  of  the  Experiment  Station  have  been  directed  to- 
wards working  out  the  details  involved  in  the  control  of  this  disease 
and  in  demonstrating  the  most  successful  methods.  Such  points  as 
when  and  how  often  to  spray ;  what  strength  of  Bordeaux  to  use ;  how 
to  prepare  the  spray  mixture  economically,  accurately  and  rapidly; 
how  to  apply  it  efficiently;  the  agencies  involved  in  the  spread  of  the 
fungus  from  plant  to  plant  and  from  field  to  field;  the  relation  be- 
tween the  weather  and  the  frequency  of  spraying. 

5.  Based  on  the  results  of  the  investigation  the  following  spraying 
scheme  is  recommended : 


i  See  California  Station  Bulletin  No.  203,  page  41. 


84  UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 

(a)  The  formula  for  Bordeaux  should  be  5  pounds  of  blue  stone, 

6  pounds  of  stone  lime  and  50  gallons  of  water.  When  the 
plants  are  small  30  to  40  gallons  of  Bordeaux  per  acre  is 
sufficient ;  but  the  amount  should  be  increased  at  each  appli- 
cation so  that  when  the  plants  are  15  or  more  inches  high 
the  spray  is  put  on  at  the  rate  of  not  less  than  100  gallons 
per  acre. 

(b)  Spray  seed  beds  at  least  twice,  especially  if  grown  on  soil 

which  produced  blighted  celery  the  preceding  year. 

(c)  After  plants  are  transplanted  into  the  field  spraying  should 

begin  when  the  first  blight  is  noticed.  In  any  event,  the 
first  spraying  should  be  given  not  later  than  six  weeks  after 
transplanting  and  one  application  a  month  should  be  given 
until  the  seasonal  rain  or  heavy  fog  comes. 

(d)  After  the  rains  have  set  in  spray  every  two  weeks  if  possible 

until  the  crop  is  harvested. 

(e)  Where  the  plants  are  over  15  inches  tall,  they  should  be  gone 

over  twice  at  each  spraying,  the  machine  moving  in  the  op- 
posite direction  the  second  time. 

(f)  Upon  the  carefulness  and  thoroughness  of  the  spraying  is  de- 

pendent to  a  large  extent  the  successful  control  of  the  blight. 
6.  Demonstration  plots  sprayed  by  the  writer  according  to  the 
above  scheme  came  through  the  season  in  first  class  shape  and  were 
almost  entirely  free  from  blight  at  harvest  time. 

FOREWORD. 
The  object  of  this  bulletin  is  to  give  an  outline  of  the  history  and 
a  description  of  the  appearance,  together  with  an  account  of  the  cause 
and  control  of  the  most  serious  disease  with  which  the  celery  growers 
of  this  State  have  to  contend.  This  publication  covers  the  work  which 
has  been  done  by  the  University  of  California  Experiment  Station  on 
this  disease  during  the  past  four  years,  but  dwells  chiefly  with  the 
observations  and  results  of  the  experiments  carried  on  in  the  celery 
fields  in  Orange  County  during  the  season  of  1909  and  spring  of  1910. 
Before  beginning  an  account  of  this  work  done  upon  the  blight,  a  few 
pages  will  be  devoted  to  a  consideration  of  the  celery  plant  and  the 
methods  of  growing  and  marketing  the  crop. 

METHODS  OF  GROWING  AND  HANDLING  CELERY. 
Of  the  early  history  of  the  celery  plant  very  little  is  known,  except 
that  it  has  been  found  growing  wild  in  the  marshes  in  Europe  and 
England.     The  flavor  of  the  wild  celery  is  very  disagreeable  and  the 


Bulletin  208.  THE  LATE  BLIGHT  OF  CELERY.  85 

plant  is  unfit  for  food.  By  careful  selection  and  improvement  in  its 
culture  it  has  been  changed  until  it  is  now  considered  one  of  the  most 
important,  refreshing  and  healthful  vegetables  grown.  On  account  of 
a  steady  growth  in  popularity  and  increase  in  consumption,  celery 
culture  has  become  a  very  important  industry.  Especially  in  Cali- 
fornia where  the  climatic  and  soil  conditions  are  so  favorable,  the  im- 
portance of  this  crop  has  grown  rapidly  until  in  Orange  County  alone, 
during  the  last  season,  over  3,000  acres  of  celery  were  grown. 

Soils  Adapted  to  Celery  Growing. — Celery  is  very  poorly  adapted 
to  worn-out  or  impoverished  land.  To  grow  a  profitable  celery  crop, 
the  soil  should  be  well  supplied  with  the  essential  elements  of  plant 
food.  This  crop  grows  well  on  nearly  all  types  of  soil  but  peat  land  is 
probably  the  best,  although  the  writer  has  seen  some  excellent  results 
on  both  adobe  and  light  sandy  loam.  As  a  rule  the  plants  are  slow  in 
starting  their  growth  on  the  heavier  soils,  but  the  yield  is  generally 
larger  and  the  celery  is  of  better  flavor  than  that  grown  on  lighter 
land. 

Varieties. — Several  varieties  of  celery  have  been  tested  in  this 
State,  but  the  Golden  Self -Blanching  is  most  popular  and  profitable. 

The  Seed  Bed. — Tt  is  very  essential  that  the  ground  to  be  used  for 
growing  the  young  plants  should  be  put  into  as  fine  a  condition  as 
possible.  The  celery  seed  is  so  small  (one  ounce  is  said  to  contain 
between  60,000  and  70,000  seed)  that  unless  the  ground  is  well  pulver- 
ized it  is  difficult  to  get  a  good  stand.  It  is  generally  estimated  that 
enough  plants  may  be  grown  on  one  acre  of  seed  bed  to  plant  twenty 
acres  in  the  field.  In  order  to  produce  healthy,  vigorous  plants,  heavy 
watering  is  the  rule  at  first,  but  as  soon  as  the  plants  have  commenced 
to  grow  the  quantity  of  water  is  reduced,  and  should  never  be  allowed 
to  stand  on  the  surface  of  the  bed.  In  order  to  accomplish  this  the 
land  must  be  well  drained.  In  the  southern  part  of  the  State  the  seed 
is  usually  sown  in  March. 

Preparation  of  the  Fields  for  the  Seedling  Plants. — While  it  is  not, 
perhaps,  as  important  to  get  the  land  in  the  field  in  as  fine  condition 
as  for  the  seed  bed,  yet  the  best  results  cannot  be  obtained  unless  the 
soil  has  been  put  into  very  fine  condition,  consequently  a  great  deal  of 
care  should  be  used  in  working  and  reworking  the  soil  previous  to 
planting. 

Irrigation. — Although  not  nearly  as  much  water  is  required  for 
the  plants  in  the  field  as  in  the  seed  bed,  celery  plants  cannot  stand 
drought  at  any  stage  of  their  growth,  consequently  a  well  controlled 


86  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

irrigation  system  is  imperative,  except  where  the  water  table  is  close 
to  the  surface.     This,  however,  is  the  exception  in  Orange  County. 

Drainage. — Good,  thorough  drainage  is  just  as  important  as  irriga- 
tion. Although  the  celery  crop  can  easily  be  ruined  if  the  water  sup- 
ply is  inadequate,  too  much  water  is  just  as  objectionable.  If  water  is 
allowed  to  stand  in  the  field  even  for  a  short  time,  the  plants  will  suf- 
fer seriously.  As  most  of  the  celery  land  is  low  and  the  ordinary 
drainage  is  poor,  an  extended  system  of  tile  drainage  has  been  made  in 
nearly  all  the  celery  fields  of  Orange  County  in  order  to  prevent 
losses  from  standing  water.  There  are  several  different  kinds  of  tile 
in  use,  the  round  tile  being  most  popular. 

Transplanting. — "When  the  plants  are  large  enough  to  be  trans- 
planted, they  are  pulled  from  the  seed  beds,  placed  in  tin  pans  and 
hauled  to  the  field,  where  they  are  planted  six  inches  apart  in  the  fur- 
rows three  and  one-half  feet  apart.  The  depth  of  the  furrows  in 
which  the  plants  are  set  is  somewhat  varied,  depending  on  the  soil, 
moisture,  and  the  size  of  the  plants.  The  average  depth  is  from  three 
to  five  inches. 

Cultivating. — After  the  plants  have  been  set  out  into  the  field  the 
cultivator  should  be  used  often  in  order  that  all  weeds  may  be  killed 
while  germinating  and  to  keep  the  moisture  in  the  ground  for  utiliza- 
tion of  the  crop.  The  field  should  be  cultivated  thoroughly  through- 
out the  entire  season,  especially  if  weed  seeds  are  abundant  in  the  soil 
or  the  amount  of  moisture  is  less  than  desired. 

Crowding. — After  the  plants  have  been  set  in  the  field  for  about 
three  weeks  or  a  month  and  have  recovered  from  the  transplanting, 
the  field  is  "crowded."  This  operation  consists  in  moving  the  earth 
away  from  the  young  plants  so  that  they  will  have  more  air  around 
them  and  to  kill  what  weeds  have  grown  so  close  to  the  plants  that  it 
is  impossible  to  reach  them  with  the  cultivator.  This  helps  to  conserve 
the  moisture  as  well. 

Rolling. — The  earth  between  the  rows  of  plants  is  left  in  a  ridge 
after  the  plants  have  been  "crowded."  A  large  wooden  roller  which 
extends  across  several  rows  is  now  used  to  flatten  down  these  ridges 
and  pack  the  soil  more  firmly.  The  roller  is  used  only  when  the  plants 
are  small,  otherwise  they  would  be  injured  by  being  crushed.  "When 
the  plants  have  grown  sufficiently  to  be  injured  by  this  rolling  of  the 
middles,  the  ridges  are  smoothed  down  by  the  cultivator. 

Splitting. — When  the  plants  are  twelve  to  fifteen  inches  tall,  earth 
from  between  the  rows  is  drawn  up  to  them.  This  is  termed  "split- 
ting."   This  should  be  done  carefully,  for,  if  the  earth  is  put  too  close 


Bulletin  208.  THE  LATE  blight  OF  CELERY. 


87 


Fig.  1. — Pulling  young  celery  plants  from  seed  bed. 


Fig.  2. — Transplanting  celery  into  the  fields. 


88  UNIVERSITY  OP  CALIFORNIA EXPERIMENT  STATION. 

or  too  high  up  on  the  plants,  they  will  become  tender  and  weak,  espe- 
cially if  the  weather  is  hot.  The  object  of  "splitting"  is  to  gradually 
encourage  the  plants  to  grow  tall  and  straight  instead  of  spreading 
out.  This  operation  is  repeated  twice  during  the  season,  the  first  time 
when  the  plants  are  fourteen  to  sixteen  inches  tall  and  the  second  time 
just  before  banking.     This  last  "splitting"  also  aids  blanching. 

Banking. — All  the  celery  grown  in  California  is  banked  with  earth 
for  blanching.  Blanching  is  done  when  the  celery  is  reaching  its 
maturity  and  is  nearly  ready  for  shipment.  This  is  the  last  field  opera- 
tion before  the  crop  is  cut.  When  the  celery  is  banked  for  the  first 
time  the  earth  is  not  drawn  very  high  on  the  plants,  but  each  time  the 
field  is  banked  the  soil  is  drawn  higher  so  as  to  firmly  hold  the  leaves 
together  and  in  an  upright  position.  If  celery  that  has  been  banked 
for  the  last  time  is  not  harvested  shortly,  it  will  soon  become  ' '  punky. ' ' 
The  length  of  time  that  it  can  safely  be  left  in  the  bank  depends  upon 
the  character  of  the  soil,  the  weather  conditions,  and  upon  the  condi- 
tion of  the  plants  themselves.  Celery  on  sandy  soil  will  keep  much 
longer  in  the  bank  than  on  adobe  or  peat  soil.  If  the  celery  has  not 
matured  or  if  the  weather  is  hot  or  moist  its  keeping  quality  will  be 
injured.  Holding  too  long  in  the  bank  will  result  in  a  wilted  and 
"punky"  product. 


Fig.  3. — Harvesting  celery. 

Cutting. — "When  the  celery  is  ready  to  harvest  a  cutting  machine 
is  used  which  cuts  off  the  plants  just  below  the  crown,  leaving  a  few 
roots  attached.  The  plants  are  then  lifted  and  shaken  free  from  soil, 
trimmed  and  thrown  in  piles  by  laborers,  who  are  usually  Japanese. 
Another  gang  of  men  then  place  the  plants  in  crates,  marking  on  each 
crate  the  number  of  dozen  it  contains.  More  men  follow,  nail  the 
crates  securely,  load  them  on  wagons  which  transport  them  to  the  rail- 
road siding,  where  they  are  ready  for  shipment  and  distribution  ,to  the 
various  markets  in  the  United  States  and  Canada. 


Bulletin  208.  THE  late  BLIGHT  OF  CELERY.  89 

Marketing. — A  very  efficient  system  has  been  developed  by  which 
this  crop  is  sold.  There  are  in  this  State  a  number  of  commission  men 
and  companies  which  sell  the  crop  for  the  growers,  but  the  largest  is 
the  California  Vegetable  Union.  This  large  organization  has  its  repre- 
sentatives in  many  of  the  leading  markets  and  by  the  use  of  telephones 
and  telegrams  market  conditions  are  known  each  day  and  the  celery 
is  shipped  to  the  points  of  greatest  demand. 

THE  LATE  BLIGHT  OF  CELEEY. 
Septoria  petroselini  Desm.,  var.  apii  Br.  and  Cav. 

History  and  Distribution. — As  before  stated,  this  disease  is  by  far 
the  worst  one  with  which  the  celery  growers  in  this  State  have  to  con- 
tend. A  comparatively  small  amount  of  literature  is  available  which 
treats  of  its  history  and  introduction  into  the  United  States.  The 
earliest  reference  to  this  disease  which  the  writer  has  been  able  to  find 
was  in  1890.  In  that  year  Briosi  and  Cavara  collected  a  few  specimens 
at  Pavia,  Italy. 2  The  first  reference  to  the  late  blight  in  the 
United  States  is  probably  in  the  year  1891.  At  that  time  it  was  noted 
in  Massachusetts  by  Humphrey.3  In  New  Jersey  by  Halsted.4 
In  Delaware  by  Chester. 5  In  a  few  of  the  bulletins  issued  by  the 
different  eastern  State  Experiment  Stations  from  time  to  time  some 
little  attention  is  paid  to  late  blight,  but  in  a  number  no  mention  is 
given.  A  bulletin  issued  by  the  New  York  Experiment  Station  in  1893 
makes  the  following  statement :  "So  far  as  could  be  determined  most 
of  the  damage  from  the  celery  leaf  spot  in  1892  in  Central  and  West- 
ern New  York  was  due  to  this  Septoria."  Prom  these  States  it  gradu- 
ally spread  west,  until  in  the  fall  of  1897  the  late  blight  began  to  be  a 
serious  menace  to  the  celery  industry  in  California. 

Introduction  into  California. — During  the  fall  of  1897  the  late 
blight  began  to  be  serious  in  this  State.  Its  presence  was  noticed  in 
a  few  of  the  fields  during  the  two  preceding  years,  but  it  did  not  occur 
commonly  enough  to  be  of  commercial  importance.  A  clipping  from 
a  letter  written  by  a  celery  grower  in  Orange  County  in  December, 
1907,  will  illustrate  the  loss. caused  by  this  disease  in  this  year:  "The 
celery  acreage  this  year  was  about  5,000  acres,  and  during  October 
our  celery  was  seriously  affected,  especially  the  early. ' '  Another  from 
the  same  vicinity,  dated  February,  1909,  reads:  "I  have  grown  celery 
for  the  last  two  years  and  both  years  the  blight  affected  it  badly." 


2  Funghi  Parisitti  Facicola,  VI,  No.  144. 

a  Annual  Eeport,  1891,  Mass.  Agr.  Exp.  Sta.,  p.  28. 

4  Annual  Eeport,  1891,  New  Jersey  Agr.  Exp.  Sta.,  pp.  255  and  256. 

s  Bulletin  from  the  Torrey  Botanical  Club  for  1891,  p.  272. 


90 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


After  its  introduction  into  Orange  County  the  blight  spread  pretty 
generally  over  the  entire  State.  A  letter  from  Santa  Paula,  dated 
June,  1909,  refers  to  blight  which  was  probably  Septoria,  that  was 
troublesome  the  preceding  year.  In  the  winter  of  the  same  year  the 
writer  made  a  trip  into  the  San  Joaquin  and  Sacramento  Counties,  in 
both  of  which  the  late  blight  was  found.  This  disease  has  also  been 
found  on  celery  grown  in  Los  Angeles,  San  Bernardino  and  Riverside 
Counties. 

A  Description  of  the  Appearance  of  the  Fungus. — The  blight  first 
affects  the  lower  outside  leaves,  where  it  is  seen  in  small,  brown  spots, 
which  later  turn  black.  These  spots  often  form  in  clusters,  but  where 
the  leaves  are  badly  affected  the  clusters  cover  the  entire  leaf  surface 
and  these  leaves  soon  fail  to  perform  their  natural  function  and  die. 


Fig.  4a. — Healthy  celery  plant. 


Bulletin  208. 


THE  LATE  BLIGHT  OF  CELERY. 


91 


In  Orange  County  the  spots  can  generally  be  seen  more  plainly  on 
the  under  side  of  the  leaves,  while  in  the  fields  in  the  vicinity  of  Stock- 
ton, which  is  situated  in  the  San  Joaquin  Valley,  the  fungus  appears 
on  the  upper  side  first.  The  difference  is  due,  no  doubt,  to  the  heavy 
fogs  so  common  at  Stockton,  which  condense  on  the  upper  surface  of 
the  leaves.  Such  tiny  drops  of  water  present  just  the  right  conditions 
for  the  germination  of  the  spores  and  consequent  infection  of  the 


Fig.  4fc. — Celery  plant  affected  with  late  blight. 


92 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


Fig.  5. — Celery  leaf  affected  with  late  blight. 

leaves.  In  many  cases,  however,  the  blight  does  not  confine  its  ravages 
to  the  leaves  but  attacks  the  stalks  also.  Here  again  it  is  seen  in  small 
black  spots,  often  in  clusters  at  first,  but  later  converging  and  covering 
the  greater  part  of  the  stalk.  When  the  plants  are  thus  infected  the 
prospect  for  ever  producing  a  marketable  product  is  very  poor,  for 
the  stalks  soon  turn  brown,  soften,  and  finally  shrivel  up. 


: *<  ,1 


Fig.  6. — Celery  stalks  affected  with  late  blight. 


Bulletin  208. 


THE  LATE  BLIGHT  OP   CELERY. 


93 


Shortly  after  the  appearance  of  the  characteristic  blight  spots  upon 
the  leaves  and  stems  described  above,  there  can  be  seen  small,  black 
pustules  or  pycnidia  in  the  center  of  the  dead  areas.  "With  age  the 
pycnidia  may  reach  the  margin  of  the  infected  area.  The  small 
pycnidia,  which  are  less  than  14  mm  m  diameter,  are  the  fruiting 
bodies  of  the  fungus.  The  pustules  at  maturity  contain  long,  cylin- 
drical, straight  or  slightly  curved,  several  septate  spores.  These  micro- 
scopic spores  measure  from  20  to  49  \x  (/x  equals  1/25,000  part  of  an 
inch)  in  length  by  1  to  l1/^  p  m  width,  and  are  the  means  by  which 


7. — Pycnidium  showing  spores  oozing  through  the 
ostiole.     (Enlarged  320  times.) 
Drawing  by  C.  N.  Jensen. 


the  fungus  is  disseminated  upon  the  same  or  to  other  plants.  (See 
fig.  7,  which  indicates  spores  oozing  from  a  mature  pycnidium.)  In 
a  general  way  the  function  of  these  spores  is  the  same  as  that  of  the 
seeds  of  higher  plants.  The  pycnidium  developes  immediately  under- 
neath the  epidermis.  Its  wall  is  from  two  to  four  cells  in  thickness 
and  is  brown  in  color.  The  mouth  or  ostiolum  is  round  and  slightly 
elevated,  and  it  is  through  this  opening  that  the  spores  ooze  out  when 
the  pycnidium  absorbs  moisture  in  foggy  or  rainy  weather. 

According  to  Klebahn    (Zeit.   fur  Pflanzenkrankheiten,  January, 
1910,  p.  8)  the  mycelium  spreads  itself  into  the  inter-cellular  spaces. 


94  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

My  observations  point  to  the  same  conclusion,  as  microscopic  leaf  and 
stem  sections  show  the  mycelium  thus  in  the  tissue.  The  fungus  does 
not  penetrate  into  the  deeper  lying  tissues  but  is  rather  limited  to  the 
cells  nearer  the  epidermis  and  a  short  distance  below. 

Means  of  Dissemination. — As  will  be  seen  by  the  above  description, 
the  spores  are  unable  to  leave  the  spore  case  or  pycnidium  until  mois- 
ture conditions  are  favorable.  This  accounts  for  the  appearance  of 
the  late  blight  after  a  heavy  fog  or  rain.  Some  of  the  agencies  by 
which  the  spores  are  spread  are :  Moisture,  wind,  insects,  men,  tools, 
horses,  etc.  But  my  observations  lead  me  to  conclude  that  irrigating 
water  when  run  through  the  furrows  in  which  the  plants  are  set  is  one 
of  the  principal  agents  in  the  spread  of  this  fungus.  The  fields  which 
show  the  greatest  amount  of  blight  previous  to  the  rains  have,  in  nearly 
every  case,  been  watered  as  above  described ;  while  in  those  fields  which 
have  been  watered  by  running  furrows  between  the  rows  of  plants 
there  is  practically  no  blight,  except  in  the  places  where  the  water  has 
run  over  into  the  celery  rows.  The  appearance  of  the  blight  at  such 
places  would  seem  to  strengthen  my  conclusions.  After  gaining  a  foot- 
hold in  the  field  the  disease  spreads  very  rapidly,  especially  if  the 
weather  is  warm  and  moist,  and  in  a  few  days  a  large  acreage  is  de- 
stroyed. The  blight  almost  invariably  makes  its  first  appearance  in 
the  low,  wet,  poorly  drained  spots  and  from  these  soon  spreads  to  other 
parts  of  the  field. 

SYNOPSIS  OF  THE  WORK  IN  ORANGE  COUNTY. 

In  Orange  County  celery  has  suffered  from  late  blight  much  more 
seriously  than  in  any  other  section  of  the  State.  This  is  not  surprising 
in  view  of  the  fact  that  this  County  produces  the  bulk  of  the  celery 
grown  in  the  State.  In  fact,  celery  culture  first  assumed  commercial 
importance  in  Orange  County  and  there  certain  fields  have  been  de- 
voted to  celery  longer  than  anywhere  else  in  the  State. 

Many  of  the  growers  have,  therefore,  joined  in  the  building  up  of 
a  large  and  well  organized  association  which  controls  the  sale  of  the 
bulk  of  the  crop.  When  the  blight  suddenly  became  serious  these  men 
were  impressed  with  the  importance  of  taking  immediate  steps  for  the 
control  of  this  damaging  disease.  Upon  receipt  of  an  urgent  letter 
from  the  interested  parties  asking  for  assistance,  a  representative  from 
the  Experiment  Station  visited  the  fields  and  investigated  the  situa- 
tion. The  season  had  advanced  so  far,  however,  that  it  was  useless  to 
start  any  experiments  in  spraying  at  that  time.  Some  spraying  had 
already  been  done  by  a  few  of  the  growers,  but  as  no  definite  plan  had 
been  followed,  the  results  were  not  very  satisfactory,  with  the  single 


Bulletin  208.  THE  LATE  BLIGHT  OP  CELERY.  95 

exception,  perhaps,  of  that  done  on  the  Golden  West  Celery  and  Pro- 
duce Company's  ranch.  The  spraying  here  was  carefully  done 
throughout  the  entire  season  and  the  manager,  writing  on  February  25, 
1908,  states:  "I  am  sorry  to  say  that  the  celery  crop  has  been  com- 
pletely wiped  out,  with  the  exception  of  that  on  our  ranch.  *  *  * 
Pleased  to  state  that  our  celery  not  only  looks  well  at  the  time  of  ship- 
ment, but  it  carries  to  destination  in  marketable  condition,  according 
to  the  reports  from  our  eastern  agents. ' '  The  results  from  the  spray- 
ing done  on  this  ranch  were  so  encouraging  that  on  March  27th,  1908, 
a  meeting  of  the  members  of  the  Association  was  held  to  arrive  at  some 
definite  plan  of  campaign  and  a  request  was  made  that  a  representa- 
tive from  the  Experiment  Station  address  the  meeting.  At  this  meeting 
it  was  decided  to  spray  the  celery  fields  the  following  year  with  Bor- 
deaux mixture  and  the  work  was  to  be  carried  on  under  the  direction 
of  Professor  H.  J.  Ramsey. 

From  this  time  on  spraying  the  celery  fields  became  a  live  problem 
with  the  growers.  Some  few  men  even  sprayed  their  seed  beds  as  soon 
as  the  plants  were  large  enough.  In  this  season  the  blight  first  ap- 
peared on  July  24th.  During  the  summer  spraying  was  done  in  many 
of  the  fields  and  very  little  blight  appeared  until  the  rains  began  in 
the  fall.  This  was  as  favorable  a  year  for  the  growth  of  the  late  blight 
as  the  preceding  one  had  been,  but  not  nearly  as  large  a  loss  was  sus- 
tained. This  was  due  to  the  fact  that  more  of  the  growers  were  spray- 
ing and  they  were  spraying  more  thoroughly  and  persistently.  A 
large  per  cent  of  the  growers  who  did  no  spraying  or  who  sprayed 
very  carelessly,  or  spasmodically,  lost  heavily.  In  general,  this  resulted 
in  a  vast  difference  in  favor  of  the  sprayed  over  the  unsprayed  fields. 
It  was,  therefore,  decided  that  in  order  to  carry  on  the  work  more 
systematically  and  in  detail  it  was  advisable  to  secure  a  man  from  the 
Experiment  Station  who  could  devote  his  entire  time  to  a  careful 
supervision  of  the  work.  Consequently,  on  August  1st,  1909,  the 
writer  proceeded  to  Smeltzer,  which  is  in  the  heart  of  the  celery  sec- 
tion, and  remained  there  throughout  the  season. 

EXPERIMENTS  AT  SMELTZER. 

The  work  at  Smeltzer  from  August  1st,  1909,  to  January,  1910, 
was  conducted  along  the  following  lines :  ( 1 )  General  field  observa- 
tions. (2)  The  collection  of  detailed  data  from  fifty-four  represen- 
tative fields.  (3)  Experiments  conducted  in  the  field  of  carefully 
measured  and  prepared  plots. 

(1)  General  Field  Observations. — General  field  observations  were 
made  as  often  as  possible,  the  object  being  to  get  a  comprehensive  idea 


96  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

of  the  extent  and  effect  of  this  disease  on  the  industry  as  a  whole.  It 
was,  of  course,  impossible  to  examine  every  field  of  the  entire  three 
thousand  acres  planted,  but  an  effort  was  made  to  secure  data  on  fields 
which  represented  as  many  of  the  different  varying  conditions  of  soil, 
drainage,  management,  etc.,  as  was  possible  in  the  time  at  my  disposal. 
Brief  chronological  notes  on  the  condition  of  the  1909  crop  follow : 

August  17 :  The  celery  around  Smeltzer  is  in  fairly  good  condition, 
although  large  numbers  of  yellow  plants  are  in  evidence,  especially  in 
those  fields  planted  late  in  the  season.  Only  two  or  three  slight  cases 
of  late  blight  have  been  noticed.  With  the  exception  of  one  field,  no 
spraying  has  been  done  this  season. 

August  26 :  The  crop  in  general  has  made  a  decided  growth  since 
last  reported  upon  and  many  of  the  fields  that  were  yellow  have  be- 
come much  greener  and  in  better  condition.  The  late  blight  has  in- 
creased to  some  extent  but  in  no  instance  has  the  damage  been  heavy 
as  yet.  The  damage  is  not  confined  to  any  one  section,  but  is  scattered 
throughout  the  entire  celery  producing  area. 

September  7 :  The  late  blight  has  increased  rapidly  and  has  gained 
quite  a  foothold  in  some  of  the  fields,  while  a  large  proportion  of  them 
show  scattering  diseased  plants  which  act  as  centers  of  infection.  As 
yet,  however,  no  plants  have  been  noted  as  killed  outright.  Only  a 
very  few  growers  have  commenced  to  spray.  While  a  cursory  survey 
might  lead  one  to  believe  that  the  crop  as  a  whole  is  in  a  better  condi- 
tion than  last  week,  a  careful  examination  shows  that  some  of  the  fields 
are  still  yellow,  and  especially  is  this  the  case  where  the  crop  is  grow- 
ing on  ground  that  was  used  for  seed  bed  earlier  in  the  season. 

September  18 :  During  the  past  week  there  have  been  some  very 
hot,  dry  days  and  much  of  the  older  celery,  especially  that  which  was 
planted  on  heavy  soil  or  on  land  that  was  used  for  seed  bed  purposes, 
has  been  badly  sunburned.  The  lower  outer  leaves  are  affected  the 
worst.  Much  of  the  late  blight  has  been  killed  by  hot,  dry  winds. 
Many  of  the  growers  are  nowT  spraying  but,  as  a  rule,  they  are  either 
not  using  enough  Bordeaux  or  are  not  mixing  it  properly. 

October  9:  During  the  past  week  one-fourth  of  an  inch  of  rain 
has  fallen,  and  this  has  been  favorable  for  the  spread  of  the  fungus. 
Alarmed  by  the  increase  of  the  disease,  attempts  at  spraying  are  being 
made  on  nearly  all  of  the  ranches. 

October  15:  At  this  date  the  blight  is  spreading  rapidly  and  has 
been  found  in  many  previously  healthy  fields.  One  field  in  particular, 
which  has  been  quite  free  from  blight  up  to  the  last  week  and  has  not 
been  sprayed,  is  now  very  badly  infected. 

October  22:    Unusually  thick,   foggy   weather  during  the  past   few 


Bulletin  208.  THE  LATE  BLIGHT  OF  CELERY.  97 

days  has  greatly  favored  the  spread  of  the  blight.  The  larger,  earlier 
planted  celery  is  the  worst  affected.  Fields  that  have  been  sprayed 
carelessly  or  not  at  all  are  in-  much  worse  condition  than  those  that 
were  cared  for.  There  is,  however,  a  little  blight  even  in  the  fields 
that  were  well  sprayed. 

November  3 :  The  situation  is  now  going  from  bad  to  worse  each 
week,  but  the  fields  that  have  been  thoroughly  and  properly  sprayed 
are,  with  very  few  exceptions,  in  first  class  condition. 

December  7 :  Since  the  last  field  observations  were  taken  three  and 
one-fourth  inches  of  rain  have  fallen,  which  has  stimulated  the  growth 
of  the  plants.  In  the  fields  which  were  used  for  seed  beds  early  in  the 
season  the  plants  are  making  very  slow  growth.  The  blight  has  been 
increasing  very  rapidly  since  the  rain,  and  some  of  the  fields  are  in  a 
serious  condition.  On  account  of  the  heavy,  washing  rains,  there  are 
many  fields  in  which,  the  foliage  shows  no  spray.  This  is  strikingly 
apparent  where  improperly  mixed  Bordeaux  was  used.  Wherever  the 
Bordeaux  wras  properly  mixed  and  applied,  it  remained  on  the  leaves 
through  the  drenching  rains.  In  the  fields  that  have  not  been  sprayed 
the  blight  is  much  worse  than  in  those  that  have. 

December  14 :  During  the  past  week  the  rainfall  has  been  over 
two  and  one-half  inches,  lasting  for  three  days,  and  as  nearly  all  the 
spray  has  been  washed  off  the  plants,  the  late  blight  has  increased  very 
rapidly.  Again  it  is  noted  that  with  no  exception  the  fields  that  have 
been  sprayed  poorly  or  not  at  all  are  nearly  ruined  by  the  late  blight. 
In  parts  of  many  fields  the  water  has  stood  around  the  plants  to  a 
depth  of  two  to  six  inches  for  several  days.  In  these  low  places  the 
damage  is  much  more  severe.  The  weather  has  been  foggy  ever  since 
the  rains  stopped,  which  has  made  the  conditions  ideal  for  the  growth 
of  the  fungus.  The  growers  are  now  spraying  the  fields  as  often  as 
possible. 

January  5 :  As  before  stated,  the  late  blight  can  be  found  in  nearly 
every  field  and  there  is  still  a  very  marked  difference  between  those 
which  were  sprayed  thoroughly  and  those  which  were  not.  In  these 
latter  fields  the  late  blight  has  practically  ruined  the  crop.  At  this 
time  it  requires  no  expert  to  realize,  after  a  glance  through  the  fields, 
that  the  control  of  this  disease  depends  upon  a  regular,  systematic  and 
intelligent  application  of  Bordeaux  mixture. 

(2)  Detailed  Observations  on  Fifty-Four  Fields. — A  detailed  rec- 
ord was  kept  of  the  above  number  of  fields,  paying  especial  attention 
to  the  dates  of  plowing,  irrigating,  transplanting  into  the  main  field, 
spraying  in  the  seed  bed,  growth  and  condition  of  the  plants,  spraying 


98  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

in  the  fields,  presence  of  early  blight,  and  the  date  the  late  blight  ap- 
peared. It  is  impracticable  here  to  present  all  of  this  data  in  detail, 
but  the  general  conclusions  will  be  of  considerable  interest. 

The  time  and  depth  of  plowing  had  no  effect  upon  the  quantity  or 
the  date  that  the  late  blight  appeared  in  the  fields.  Irrigation  is  the 
one  field  operation  which  bears  a  close  relation  to  the  abundance  or 
scarcity  of  the  late  blight.  The  use  of  irrigation  water  in  too  large 
quantities  so  that  there  is  standing  water  around  the  plants  makes  one 
of  the  most  favorable  conditions  for  the  development  of  the  late  blight. 
In  Orange  County  there  are  two  systems  of  irrigation  in  use :  Sub- 
irrigation  through  tile,  and  ordinary  surface  irrigation  in  furrows. 
In  the  fields  that  were  sub-irrigated  the  late  blight  was  very  much  less 
(up  to  the  time  of  the  rains)  than  in  those  which  were  irrigated  the 
latter  way.  Some  of  the  fields  were  irrigated  by  running  furrows  made 
between  the  rows  of  plants,  while  many  others  were  irrigated  by  run- 
ning the  water  down  the  rows  of  celery.  As  has  been  before  stated, 
this  method  is  a  very  unwise  one  to  follow.  Good  drainage  is  fully  as 
important  as  skillful  irrigation,  for  the  diseased  plants  are  invariably 
found  first  and  worst  in  the  poorly  drained  spots.  This  is  particularly 
noticeable  this  season. 

No  very  striking  advantage  was  found  this  year  in  spraying  the 
plants  in  the  seed  beds,  although  this  practice  is  strongly  advocated  as 
the  expense  and  labor  involved  is  very  small  in  comparison  with  the 
results  that  may  be  accomplished  some  years.  Especially  is  this  true 
if  the  seed  bed  is  on  land  that  grew  diseased  plants  the  previous  season. 

A  record  was  kept  of  the  dates  upon  which  each  of  the  fields  we 
sprayed,  and  the  results  bring  out  a  very  important  fact  and  are  very 
encouraging.  A  few  of  the  growers  began  spraying  their  fields  about 
the  first  of  September,  and  by  the  latter  part  of  the  month  many  of 
the  fields  had  been  gone  over  once.  Nearly  all  the  growers  who  had 
sprayed  at  all  had  begun  operations  by  the  middle  of  October,  while 
some  of  the  earliest  planted  fields  had  by  that  time  been  sprayed  twice. 
The  general  aim  was  to  spray  the  fields  every  two  or  three  weeks  dur- 
ing the  entire  season,  but  on  account  of  the  regular  routine  of  ranch 
work  it  was  not  always  possible  to  do  so.  After  the  winter  rains  began 
it  was  often  impossible  to  get  into  the  fields  as  soon  as  desirable. 

The  first  late  blight  in  the  1909-10  crop  seen  by  the  writer  was 
found  on  August  17th.  From  this  time  on  the  late  blight  increased, 
but  not  until  the  rains  came  did  it  do  much  damage.  The  earlier 
planted  larger  celery  was  the  first  to  become  infected,  and  also  that 
which  was  not  sprayed  or  sprayed  carelessly. 


Bulletin  208.  THE  LATE  BLIGHT  OF  CELERY.  99 

(3)  Experiment  Field. — The  object  of  the  plot  experiments  was  to 
determine,  if  possible,  the  best  time  or  times  to  spray  in  order  to  con- 
trol the  late  blight.  This  field  contained  one  acre  of  land  and  was 
situated  at  Smeltzer.  The  soil  was  a  heavy  loam  and  was  in  excellent 
condition,  sub-irrigated  and  drained.  This  field  has  been  planted  con- 
tinuously to  celery  for  the  past  fourteen  years.  It  was  plowed  on  May 
first,  irrigated  on  June  1st,  and  the  celery  plants  were  set  on  August 
1st.  As  the  work  of  spraying  could  be  carried  on  much  more  satisfac- 
torily on  small  areas,  this  tract  of  land  was  sub-divided  into  fifty 
plots,  each  containing  an  area  of  one  fiftieth  of  an  acre,  so  that 
each  consisted  of  six  rows  of  celery  forty-one  and  four-tenths  feet  in 
length.  Each  plot  was  large  enough  to  secure  reliable  results  and 
small  enough  so  that  the  work  could  be  done  thoroughly  and  on  time. 

Of  course  it  will  be  understood  that  the  spraying  with  Bordeaux 
mixture  for  any  fungus  disease  has  for  its  object  the  prevention  of  the 
disease  rather  than  its  cure.  It  is  well  known  that  the  spores  of  the 
fungus  cannot  germinate  and  infect  the  leaf  but  will  be  killed  if  they 
come  in  contact  with  copper  sulphate  or  blue  stone.  A  solution  of 
blue  stone  alone  will  kill  the  leaves,  hence  the  lime  is  added  to  prevent 
this.  It  will  be  seen,  therefore,  that  the  disease  will  be  prevented  only 
to  the  extent  to  which  the  Bordeaux  covers  all  the  surface  of  the  leaves 
and  stalks.  Hence  the  necessity  for  thorough  work.  If  new  leaves 
grow  out,  these  in  turn  must  be  covered  with  spray  and,  should  a 
drenching  rain  wash  the  Bordeaux  off,  it  is  necessary  to  spray  again 
and  as  soon  as  possible. 

The  spraying  of  these  experimental  plots  was  carried  out  accord- 
ing to  the  schedule  given  below : 

Plot  Number.     Dates  of  Spraying. 


1 

9/15;  10/15;  11/15;  12/15. 

2 

9/15;  10/1;  10/15;  11/1;  11/15;  12/1;  12/15;  1/1. 

3 

9/15;  11/15. 

4 

9/15;  11/1;  11/15;  1/1. 

5 

9/15;  12/15. 

6 

9/15;  12/1;  12/15. 

7 

9/15. 

8 

9/15. 

9 

9/15;  10/15. 

10 

9/15;  11/15. 

11 

9/15;  12/15. 

12 

9/15. 

13 

9/15. 

14 

Spray  when  necessary;  10/1;  11/1;  12/15;  1/1. 

15 

Check;  left  unsprayed. 

100  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


*5  .)     I   il    I     I  Ik    I     L-iS-J     I    U     '     '    fe    I     I L 

I'1!^.  8. —  Plan  of  the  experiment  field.     The  proportion  of  black   in 
each  plot  indicates  the  amounl  <>f  blight. 


ULLETIN  208. 

THE  LATE  BLIGHT  OF  CELERY. 

16 

10/1;  11/1;  12/;  1/1. 

17 

10/1;  10/15;  11/1;  11/15;  12/1;  12/15;  1/1. 

18 

10/1;  12/1. 

19 

10/;  10/15;  12/1;  12/15. 

20 

10/1;  1/1. 

21 

10/1;  10/15;  1/1. 

22 

10/1. 

23 

10/1;  10/15. 

24 

10/1;  11/1. 

25 

10/1;  12/1. 

26 

10/1. 

27 

Spray  when  necessary;  10/1;  11/1;  12/15;  1/1 

28 

11/1;  11/15;  12/1;  12/15;  1/1. 

29 

11/1;  12/1;  1/1. 

30 

Check;  left  unsprayed. 

31 

11/1;  1/1. 

32 

11/1;  11/15;  1/1. 

33 

11/1. 

34 

11/1;  11/15. 

35 

11/1;  12/1. 

36 

11/1. 

37 

Spray  when  necessary;  10/1;  11/1;  12/15;  1/ 

38 

Check;  left  unsprayed. 

39 

12/1;  1/1. 

40 

12/1;  12/15;  1/1. 

41 

12/1. 

42 

12/1;  12/15. 

43 

12/1;  1/1. 

44 

12/1. 

45 

Spray  when  necessary;  12/1;  12/15;  1/1. 

46 

Check;  left  unsprayed. 

47 

1/1. 

48 

1/1. 

49 

Check;  left  unsprayed. 

50 

Check;  left  unsprayed. 

101 


Spraying  was  begun  on  September  16th  and.  at  this  time  there  was 
no  blight  on  any  of  the  plots. 

On  October  1st  the  plots  that  were  sprayed  on  September  16th  had 
pushed  out  so  many  new  leaves  that  it  at  once  became  apparent  that  if 
celery  was  to  be  sprayed  for  the  blight  in  an  ideal  way,  it  would  of 
necessity  be  an  almost  continuous  performance.  But  spraying  costs 
money  and  the  question  which  at  once  assumed  paramount  importance 
was :  Just  how  much  time  may  we  safely  allow  to  elapse  bet  ween 
sprayings  without  giving  the  fungus  a  chance  to  take  hold  ?  From  this 
time  to  the  end  of  the  season  my  best  efforts  were  devoted  to  the  solu- 
tion of  this  question. 

During  September,  October  and  November,  the  celery  made  a  rapid 


102  UNIVERSITY  OP  CALIFORNIA EXPERIMENT  STATION. 

growth  and,  depending  upon  various  conditions,  it  required  from  ten 
to  twenty-five  days  for  the  new  growth  to  so  over-top  the  old  sprayed 
leaves  as  to  give  the  field  the  appearance  of  not  having  been  sprayed. 
The  blight  first  appeared  on  November  1st,  in  plot  No.  37,  which  had 
been  sprayed  just  a  month  previous.  At  this  time  five  diseased  plants 
were  noted,  two  adjacent  plants  being  badly  affected,  while  the  other 
three  in  a  different  part  of  the  plot  showed  only  a  few  spotted  leaves. 

On  November  15th  a  slight  scattering  of  blight  was  found  in  plot 
No.  4,  Avhich  had  been  sprayed  twice.  Between  November  1st  and  De- 
cember 16th  there  occurred  a  rainfall  of  five  and  three-quarter  inches. 
This  started  the  late  blight  in  many  of  the  plots  but  as  a  whole  the  field 
is  in  good  condition.  The  plants  vary  somewhat  in  size,  due  to  the 
character  of  the  soil,  but  the  average  plants  are  eighteen  to  twenty 
inches  high.  At  this  date  the  plots  apparently  free  from  blight  are : 
Nos.  1,  2,  4,  7,  8,  9,  14,  16,  17,  21,  23,  24,  25,  26,  27,  28,  29,  31,  33, 
34,  35,  38,  44. 

Those  showing  a  slight  scattering  of  blight  are :  Nos.  3,  6,  10,  18, 
19,  22,  30,  32,  36,  39,  40,  41. 

Those  badly  affected  are :    Nos.  5,  11,  12,  13,  15,  20,  37,  42,  43,  45. 

The  effect  of  the  rain  on  the  spray  is  shown  by  the  following :  No 
spray  is  showing  on  the  plants  in  plots  Nos.  1,  3,  5,  7,  8,  9,  11,  12,  13, 
14,  15,  20,  21,  22,  23,  24,  26,  27,  30,  31,  33,  36,  37,  38,  46. 

A  little  spray  is  showing  on  plots  No.  4,  19,  25,  32,  34,  39,  40,  41,  42. 

A  fair  coating  of  spray  is  apparent  on  plots  No.  6,  10,  35,  43,  44,  45. 

A  good  coating  of  spray  is  still  on  the  leaves  on  plots  No.  2,  16,  17, 

18,  28,  29. 

"While  it  is  difficult  to  draw  any  very  definite  conclusions  from  the 
figures,  they  indicate  several  very  interesting  points.  With  no  excep- 
tion, every  plot  that  shows  considerable  late  blight  has  been  sprayed 
only  once  or  not  at  all,  and  the  plots  sprayed,  with  the  exception  of 
No.  20,  were  sprayed  only  on  September  15th.  Plot  No.  20  was  sprayed 
only  on  October  1st.  The  plots  showing  the  most  late  blight  are  those 
that  show  the  least  amount  of  spray  on  their  leaves.  The  plots  that 
show  a  good  coating  of  spray  are  those  which  were  sprayed  twice  or 
more  and  on  all  of  these  the  spray  was  put  on  December  1st. 

January  3  :  The  weather  during  the  past  week  has  been  very  favor- 
able for  the  growth  of  the  late  blight,  which  has  spread  pretty  gen- 
erally all  over  the  field  and  some  of  the  plots  are  nearly  ruined  by  it. 
The  condition  of  the  plots  at  this  time  is  as  follows : 

Those  free  from  blight  are :    Nos.  2,  4,  17,  28. 

Those  showing  very  little  blight  are:     Nos.  1,  3,  9,  10,  14,  16,  18, 

19,  21,  23,  24,  25,  27,  29,  32,  33,  34,  35. 


Bulletin  208.  THe  LATE  BLIGHT  OF  CELERY.  103 

The  following  plots  had  some  blight,  though  not  very  serious  :  Nos. 
6,  8,  26,  31,  40. 

Those  showing  considerable  blight  are :  Nos.  7,  11,  13,  30,  36,  37, 
39,  41,  42,  43,  44. 

Those  very  badly  blighted  are :  Nos.  5,  12,  15,  20,  22,  38,  45,  46, 
47,  48,  49,  50. 

In  spite  of  the  rain  plots  No.  2,  17,  19,  27,  and  28  still  show  a  good 
coating  of  spray,  while  29  has  a  fair  coating. 

By  comparing  the  observations  taken  two  weeks  ago  and  those  of 
today  it  will  be  noticed  that  of  the  four  plots  which  are  still  free  from 
blight,  three  still  have  a  good  coating  of  spray.  The  late  blight  has 
increased  in  all  but  fourteen  plots.  Thirteen  out  of  eighteen  plots 
that  are  now  but  little  blighted  were  healthy  up  to  December  15th,  the 
other  five  being  in  about  the  same  condition  that  they  were  two  weeks 
ago.  Of  the  five  plots  that  now  have  some  late  blight  in  them  (al- 
though not  enough  to  be  serious)  three  had  none  up  to  December  15th 
and  the  remaining  had  up  to  that  time  only  a  slight  scattering.  Of 
the  plots  that  now  show  considerable  blight,  two  had  none  December 
15th,  three  had  only  a  very  slight  scattering,  and  the  remaining  ones 
were  in  about  the  same  condition.  Of  the  twelve  plots  that  are  now 
nearly  ruined  by  this  disease,  one  had  no  late  blight  on  December  15th, 
one  had  a  little,  and  ten  were  badly  blighted,  though  they  are  now  in 
a  much  worse  condition.  With  one  exception,  the  plots  that  now  have 
no  late  blight  in  them  are  the  ones  that  have  been  sprayed  every  two 
weeks,  and  all  in  this  group  were  sprayed  for  the  first  time  on  or 
before  November  1st. 

The  plots  that  are  in  the  worst  condition  are  the  ones  that  have  not 
been  sprayed  at  all,  or  have  been  sprayed  for  only  part  of  the  season. 
Out  of  this  group  of  twelve  plots,  five  have  received  no  spray,  four 
have  been  sprayed,  only  once,  two  have  been  sprayed  twice,  while  one 
has  been  sprayed  three  times,  commencing  with  December  1st.  All  the 
plots  that  have  been  sprayed  only  once  a  month  have  a  little  late  blight 
in  them,  and  plot  No.  39,  which  was  sprayed  for  the  first  time  on 
December  1st,  is  badly  blighted.  With  the  exception  of  plot  No.  33,  all 
those  that  were  sprayed  every  three  months  are  practically  ruined  by 
the  late  blight.  All  the  checks  which  were  not  sprayed  at  all  are 
practically  ruined. 

CONCLUSIONS  AS  TO  METHODS  OF  CONTKOL. 

The  writer  is  fully  alive  to  the  danger  of  drawing  premature  con- 
clusions from  the  results  of  one  season's  work,  still  these  results  have 
been  so  emphatic  and  consistent  that  it  was  decided  to  publish  them 
at  this  time. 


104  UNIVERSITY  OP  CALIFORNIA EXPERIMENT  STATION. 

For  the  prevention  of  late  blight  celery  plants  should  be  sprayed 
at  least  twice  while  still  in  the  seed  bed.  A  third  spraying  should  be 
given  about  a  month  or  six  weeks  after  the  plants  have  been  set  in  the 
field.  The  exact  time  for  the  third  spraying  should  be  governed  by  the 
size  of  the  plants,  time  of  year,  weather,  and  the  condition  of  the  soil 
as  regards  moisture,  et  cetera.  After  this  they  should  be  sprayed  once 
a  month  until  the  rains  begin  or  more  often,  should  the  blight  appear. 
From  this  time  on  a  critical  watch  should  be  kept  and  spray  applied  as 
often  as  necessary  to  keep  the  leaf  surface  well  covered,  but  in  no  case 
allow  more  than  two  weeks  to  elapse  between  sprayings.  This  is  nec- 
essary in  order  to  protect  the  new  leaves  which  continue  to  push  out. 
This  should  be  continued  until  harvest. 

Application  of  the  Fungicide. — Bordeaux  mixture  should  be  ap- 
plied in  the  form  of  a  very  fine  mist  and  this  necessitates  a  high  pres- 
sure machine.  If  a  low  pressure  machine  is  used  and  the  mixture 
sprinkled  on  the  plants  in  the  form  of  drops,  it  merely  runs  off  on  the 
ground  and  is  wasted.  While  the  plants  are  small,  going  over  the  field 
once  is  sufficient  for  each  application.  When  the  plants  have  reached 
a  height  of  fifteen  inches  it  will  be  necessary  to  go  over  the  field  twice 
for  each  application.  To  do  this  to  best  advantage,  it  is  well  to  go 
over  the  field  in  the  ordinary  wTay,  then  go  back  to  the  first  row 
sprayed  and  proceed  in  the  opposite  direction  from  that  traveled  be- 
fore. This  plan  not  only  tends  to  wet  both  sides  of  the  leaves,  but  it 
allows  time  for  the  first  spray  to  dry.  If  the  machine  returns  at  once 
on  the  same  row,  the  drops  of  liquid  will  coalesce  and  run  off  the 
plants.  Many  persons  are  puzzled  to  know  just  how  much  spray  to 
put  on.  They  should  realize  that,  if  the  tiny  particles  of  spray  are 
not  thick  enough  on  the  leaf  the  fungus  spores  may  gain  entrance  in 
between  them,  while  if  they  are  put  on  too  thick  they  will  coalesce 
into  drops  and  run  off  the  plant.  Therefore,  the  skillful  sprayer  will 
attempt  to  strike  a  medium  and  cover  the  foliage  as  thoroughly  as 
he  can  with  the  mist.  "While  the  plants  are  yet  small  thirty  to  forty 
gallons  of  Bordeaux  will  be  required  to  the  acre,  but  when  the  crop 
is  fifteen  inches  high  it  will  require  at  least  one  hundred  gallons  per 
acre  to  cover  the  foliage  in  the  way  described  above. 

The  Preparation  of  Bordeaux  Mixture. — On  preparing  Bordeaux 
mixture,  the  first  step  is  to  make  up  a  quantity  of  stock  solution  of 
the  copper  sulphate  and  lime.  It  is  very  important  that  this  be  done 
carefully.  The  first  step  is  to  nearly  fill  two  fifty-gallon  barrels  with 
water.  One  is  to  be  used  for  the  blue  stone  and  one  for  the  lime. 
Next,  weigh  out  fifty  pounds  of  blue  stone  in  a  sack  and  suspend  it 
near  the  surface  of  the  water  in  one  of  the  barrels.     So  placed,  it  will 


Bulletin  208. 


THE  LATE  BLIGHT  OF  CELERY. 


105 


dissolve  much  faster  than  if  placed  in  the  bottom.  Next,  weigh  out 
fifty  pounds  of  stone  lime  and  after  carefully  slaking  it  by  adding 
water,  a  little  at  a  time,  pour  into  the  other  barrel.  It  is  very  essen- 
tial that  the  lime  be  well  slaked  and  this  is  best  done  by  putting 
fifteen  or  twenty  pounds  at  a  time  into  a  tub  and  adding  water  little 
by  little  until  it  becomes  a  thick,  smooth  paste. 

It  is  also  very  important  that  the  stock  solutions  should  be  diluted 
before  they  are  mixed.  According  to  the  above  directions,  one  gallon 
of  the  stock  solutions  will  contain  one  pound  of  blue  stone  or  lime. 
Two  other  barrels  should  now  be  filled  with  nearly  enough  water  to 
make  a  tank  full  of  mixture,  and  the  required  amount  of  stock  solu- 
tion added  to  each.     Thus,  the  two  solutions  are  diluted  separately 


Fig.  9. — Mixing  Bordeaux. 


106  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


Fig.  10. — Mixing  Bordeaux. 


Fig.  11. — Mixing  Bordeaux. 


Bulletin  208.  THE  late  blight  op  celery.  107 

and  are  ready  to  be  mixed.  The  mixing  should  be  done  while  the  two 
solutions  are  running  into  the  tank  simultaneously.  One  very  satis- 
factory way  of  mixing  is  by  means  of  a  pump  shown  in  Figure  9. 
This  has  two  pieces  of  hose,  one  drawing  the  dilute  lime  and  the  other 
the  dilute  blue  stone,  while  a  single  pipe  delivers  the  mixture  to  the 
tank.  The  object  of  this  care  is  to  prepare  the  Bordeaux  in  such  a 
manner  that  it  will  remain  in  suspension  in  the  water  for  as  long  a 
time  as  possible.  Another  very  good  way  of  running  the  solutions  into 
the  tank  is  shown  in  Figs.  10  and  11.  All  of  these  platforms  perform 
the  work  well  and  there  is  very  little  choice  between  them.  The  plat- 
form is  usually  built  over  the  well  or  ditch  from  which  the  water  is 
taken  and  the  floor  is  six  inches  to  one  foot  from  the  top  of  the  spray 
tank.  It  is  large  enough  to  hold  six  barrels ;  nine  feet  square  being  a 
convenient  size.  The  barrels  are  placed  in  a  row,  the  center  two  being 
used  for  diluting.  Stopcocks  near  the  bottom  of  these  are  attached 
to  hose  which  convey  the  contents  to  a  trough  which  delivers  the  mix- 
ture into  the  spray  tank  through  a  thirty-mesh  sieve.  Some  water  is 
usually  added  later  to  fill  the  tank. 

In  order  to  illustrate  the  importance  of  properly  mixing  the  Bor- 
deaux, the  writer  contrived  the  experiments  shown  in  Figs.  12,  13,  14, 
and  15.  Fig.  12  was  taken  after  the  Bordeaux  was  mixed  and  undis- 
turbed for  two  hours,  fig.  13  shows  the  same  mixtures  after  six  hours, 
and  fig.  14  after  an  elapse  of  seventy-two  hours.  In  figs.  12,  13,  and  14, 
bottle  No.  1  contains  Bordeaux  in  which  the  blue  stone  and  lime  were 
diluted  and  poured  into  the  bottle  simultaneously.  Bottle  No.  2  con- 
tains Bordeaux  prepared  by  pouring  the  blue  stone  and  lime  solutions 
together  concentrated  and  then  diluting  to  the  same  strength  as  No.  1. 
No.  3  was  mixed  in  exactly  the  same  manner  as  No.  1  except  that  the 
solutions  were  not  diluted  before  being  mixed. 

"While  the  mixture  made  by  not  diluting  the  stock  solutions  before 
mixing  is  far  better  than  the  one  which  was  mixed  concentrated  and 
then  diluted  to  the  required  strength,  it  is  not  as  good  as  the  mixture 
made  by  first  diluting  the  stock  solutions.  The  longer  the  Bordeaux 
is  allowed  to  stand,  the  greater  the  difference  until  after  seventy-two 
hours;  see  fig.  14. 

To  still  further  show  the  difference  due  to  different  methods  of 
mixing,  the  writer  prepared  an  exhibit  shown  in  fig.  15,  bottles  4,  5, 
and  6.  Bottle  No.  5  contains  properly  mixed  Bordeaux ;  No.  6  has  had 
the  lime  poured  into  the  water,  then  a  concentrated  solution  of  blue 
stone.  Bottle  No.  4  has  had  the  blue  stone  solution  poured  into  the 
water  and  then  the  concentrated  solution  of  lime.  Fig.  No.  15  was 
taken  after  the  mixture  had  stood  for  three  hours  undisturbed.     This 


108  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


Fig.  12.— See  page  106. 


Fig.  13.— See  page  106. 


Bulletin   208.  THE  LATE  BLIGHT  OF  CELERY. 


109 


B.  **         fisfSBfiHg! 

H  ^SseI 

Fig.  14.— See  page  106. 


Fig.  15. — See  page  106. 


110 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


illustrates  very  conclusively  that  Bordeaux  must  be  prepared  by  first 
diluting  the  stock  solutions  before  they  are  mixed  and  the  mixing 
should  be  done  while  they  are  being  poured  into  the  tank. 

Another  important  question  which  has  not  been  fully  worked  out 

is :     Just  what  strength  of  Bordeaux  should  be  used  for  celery  late 

blight?     The  strength  used  on  our  experiment  plots  and  in  the  main 

celery  fields  proved  very  satisfactory  and  is  recommended  accordingly. 

Strength  of  Bordeaux  recommended : 

Blue  stone,  5  lbs. 

Stone  lime,  6  lbs. 

Water,  50  gallons. 


Fig.  16. — Small  capacity  spraying  machine;  power  derived  from  gear  wheels. 


Spraying  Machinery. — There  are  two  different  types  of  spraying 
machines  used  in  Orange  County.  The  oldest  and  probably  the  most 
common  in  use  is  shown  in  Fig.  16.  The  spray  tank  has  a  capacity  of 
150  gallons  and  is  supported  on  a  two-wheeled  vehicle  drawn  by  two 
horses.  The  pump  which  sprays  the  material  onto  the  plants  is 
worked  by  a  chain  which  runs  on  a  gear  fastened  to  one  of  the  wheels. 
It  is  possible  to  get  a  pressure  of  one  hundred  pounds  or  more.  This 
machine  sprays  four  rows  at  a  time  and  it  is  possible  to  spray  ten 
acres  a  day  going  over  the  plants  once.  As  will  be  seen  by  the  figure, 
two  nozzles  are  used  for  each  row,  so  as  to  cover  the  stalks  as  well  as 
the  tops  with  the  spray  mixture.     While  this  machine  does  fairly 


Bulletin  208.  THe  late  blight  of  celery.  Ill 

thorough  work,  it  has  several  disadvantages.  The  main  difficulty  is 
to  maintain  a  steady  pressure,  as  the  pressure  is  wholly  dependent 
upon  the  rate  the  machine  moves.  When  the  machine  is  turning  at 
the  ends  of  the  rows  the  pressure  at  once  drops  and  as  it  cannot  be 
brought  up  again  until  the  machine  is  under  way,  several  plants  will 
be  left  unsprayed.  The  pull  on  the  horses  is  very  heavy,  especially 
when  the  fields  are  muddy. 

By  far  the  most  desirable  type  of  spraying  machine  is  shown  in 
Fig.  17.  This  machine  gives  great  satisfaction,  and  the  use  of  a  ma- 
chine of  this  type  is  strongly  advocated.  The  pressure  is  maintained 
by  the  gasoline  engine,  which  is  situated  in  the  rear  of  the  tank.     A 


Pig.  17. — Large  capacity  spraying  machine;  power  derived  from  gasolene  engine. 

spraying  machine  as  large  as  this  one  is  not  always  economical,  espe- 
cially for  the  growers  who  have  only  a  few  acres  of  celery.  But  for- 
tunately there  are  several  small  engines  on  the  market  which  are  suit- 
able for  this  class  of  growers.  The  strong  point  in  favor  of  this  type 
of  machine  lies  in  its  ability  to  maintain  a  steady  high  pressure, 
whether  the  sprayer  is  moving  or  not.  The  churn  in  the  tank  which 
keeps  the  mixture  well  agitated  is  also  run  by  the  engine.  This  ma- 
chine, which  is  shown  in  Fig.  17  sprays  six  rows  of  celery  at  a  time 
and  will  go  over  twenty  acres  a  day,  spraying  the  plants  once.  The 
cost  of  these  engines  varies  from  fifty  to  four  hundred  dollars,  depend- 
ing upon  their  size. 

It  is  very  essential  in  order  to  apply  the  spray  regularly  and  thor- 
oughly that  the  spraying  machine  should  be  kept  in  good  condition. 


112  UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 

The  nozzles  will  soon  be  in  bad  shape  if  not  cared  for,  dne  to  the 
action  of  the  blue  stone,  and  in  a  short  time  the  holes  through  which 
the  spray  passes  will  be  so  large  that  the  contents  of  the  tank  will  be 
poured  instead  of  sprayed  onto  the  plants.  To  avoid  this  condition, 
the  nozzle  should  be  washed  in  clean  water  at  the  end  of  each  day 
that  the  spray  is  used,  or  better  still,  water  should  be  run  through 
all  the  pipes. 

The  Cost  of  Spraying  and  the  Profits  Resulting  Therefrom. — If 
the  5-6-50  Bordeaux  formula  is  used  and  calculating  the  blue  stone  at 
5!/4^  per  pound  and  the  lime  at  1^  per  pound,  the  material  necessary 
to  make  up  50  gallons  of  the  Bordeaux  will  cost  32^.  The  total  cost 
of  the  materials  used  per  acre  for  the  entire  season  will  vary  from 
$2.00  to  $5.28. 

In  order  to  show  the  profits  from  spraying,  the  crop  grown  in  the 
fall  of  1907  and  spring  of  1908  will  be  referred  to.  As  has  already 
been  mentioned,  this  was  the  season  in  which  the  blight  was  so  dis- 
astrous. Six  thousand  acres  were  planted  to  celery  in  Orange  County 
this  year,  and  the  loss  from  this  disease  is  estimated  at  $550,000.00° 
In  fact,  practically  the  bulk  of  the  crop  was  ruined.  With  the  excep- 
tion of  80  acres  of  celery  grown  on  the  Golden  West  Ranch  no  spray- 
ing was  done.  The  celery  in  this  field  was  sprayed  thoroughly  during 
the  entire  season  and  very  few  plants  were  lost  by  the  blight.  The 
gross  returns  from  the  celery  grown  on  this  80-acre  tract  ivas 
$27,000. 

While  it  is  quite  difficult  to  estimate  the  actual  losses  from  this 
disease  during  the  last  two  seasons,  the  following  estimates  were  made 
by  one  of  the  directors  of  the  Orange  County  Celery  Growers'  As- 
sociation : 

"The  loss  due  to  the  late  blight  in  1908  was  approximately  $25,000 
and  in  1909  the  total  loss  was  $10,000.  In  both  seasons  much  of  the 
loss  was  caused  by  growers  who  would  not  spray  thoroughly  nor  mix 
the  spray  properly." 

The  season  of  1909  was  much  more  favorable  for  the  growth  of 
the  blight  than  the  previous  year,  although  not  nearly  the  amount  of 
loss  occurred  owing  to  the  fact  that  more  of  the  growers  were  spraying 
persistently  and  thoroughly. 

The  actual  cost  of  buying  the  materials  and  applying  them  is  prac- 
tieally  nothing  in  comparison  to  the  results  derived.  The  actual  cost 
of  spraying  is  dependent  on  the  number  of  times  the  spray  is  applied. 
This  in  turn  is  dependent  upon  several  conditions,  namely :  the  time 
of  harvesting,  weather  conditions  and  the  thoroughness  of  the  work. 


e  See  Cal.  Exp.  Sta.  Bull.  No.  203,  page  41. 


Bulletin  208.  the  late  BLIGHT  OF  CELERY.  1 1 3 

Celery  that  is  shipped  in  November  will  have  been  sprayed  pos- 
sibly only  four  or  five  times,  while  celery  that  is  not  harvested  until 
March  will  probably  have  been  sprayed  ten  or  eleven  times.  Not  only 
the  time  at  which  the  crop  is  harvested  will  indicate  the  number  of 
sprayings  necessary,  but  the  climate  and  especially  moisture  condi- 
tions. It  has  been  indisputable  so  far  that  the  earliness  of  the  rains 
and  fogs  determine  the  time  of  prevalence  of  the  blight  and  a  large 
amount  of  rain  or  fog  is  certain  to  be  followed  by  a  rapid  incraese 
of  the  disease. 

And  lastly  I  would  emphasize  the  fact  that  skillful  and  effective 
spraying,  looking  toward  the  elimination  of  the  sources  of  infection 
will  greatly  reduce  the  cost  of  protecting  the  crop.  This  is  especially 
true  where  thorough  spraying  is  the  rule  in  all  adjacent  celery  fields. 


OTHEE  FUNGUS  DISEASES  AND  INJUEIOUS  INSECTS. 

Aside  from  the  Late,  or  Winter  Blight,  there  are  several  other 
troubles  which  result  in  some  damage  to  the  celery  crop.  Some  of 
these  will  be  briefly  discussed. 

Early  Blight  (Cercospora  apii  Fr.). — This  disease  occurs  more  or 
less  generally  throughout  the  State,  yet  it  has  never  been  the  cause 
of  serious  loss.  It  appears  on  the  plants  early  in  the  season,  the  lower 
outside  leaves  becoming  infected  first.  It  soon  spreads  to  the  inner 
leaves,  but  is  never  found  on  the  stalks.  The  threads  of  this  fungus 
work  themselves  into  the  tissues  and  cause  brown  spots  generally  in 
the  center  of  the  leaves.  This  disease  often  affects  the  plants  while  in 
the  seed  bed.    Hot,  moist  weather  is  most  favorable  to  its  growth. 

If  the  disease  becomes  serious,  spray  with  Bordeaux  mixture  as 
described  for  Late  Blight.  Thorough  cultivation  and,  in  fact,  any 
operation  that  will  favor  quick  growing,  healthy  plants  is  strongly 
recommended. 

Stem  Rot  (Sclerotinia) . — This  disease  is  found  on  the  plants  only 
late  in  the  season  after  the  rains  have  started.  Although  this  is  not 
uncommon,  it  does  very  little  damage.  It  is  more  prevalent  in  places 
that  are  poorly  drained  and  has  been  noticed  in  some  instances  where 
a  large  weed  rotted  next  to  celery  plant. 

Boot  Rot  (Fusarium) . — This  disease  occurs  only  in  extremely  wet 
places;  generally  more  abundant  after  the  rains  have  started.  Good 
drainage  and  cultivation  will  control  it.  No  large  losses  have  been 
reported  due  to  this  fungus. 


114  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

Damping  Off. — Very  little  trouble  is  experienced  with  damping  off 
of  celery.  It  attacks  the  young  plants  while  they  are  in  the  seed  bed, 
especially  if  the  bed  is  kept  too  wet.  If  troublesome,  improve  the 
drainage  condition  so  as  to  get  rid  of  the  surplus  water. 

Insect  Enemies. — During  the  past  season  the  celery  fields  have  suf- 
fered severely  from  attacks  of  the  Celery  Leaf- Tver  (Phlyctaenia  fer- 
rubalis  Hbn.).  This  insect  has  been  seen  in  small  numbers  previous 
to  this  year,  but  had  caused  no  large  losses.  This  season,  however, 
many  acres  of  celery  were  almost  totally  destroyed  by  it.  The  worms 
commenced  their  devastations  early  in  September  and  became  worse 
up  to  the  time  the  cold  weather  and  rains  set  in,  and  from  then  to 
the  last  of  the  season  they  were  present  in  most  of  the  fields,  although 
they  were  not  very  active. 

Several  experiments  were  carried  on  during  the  past  season  in 
order  to  find  an  effective  remedy  for  their  control,  but  the  season  had 
advanced  so  far  and  the  plants  were  so  large  that  it  was  extremely 
difficult  to  get  the  spray  down  to  that  part  of  the  plants  where  the 
insects  were  feeding.     The  following  sprays  were  tried: 

No.  1     Paris  Green 1  pound 

Water  200  gallons 

Kerosene  Emulsion. 

No.  2     Kerosene    7  gallons 

Hard   Soap 2  pounds 

Water  100  gallons 

No.  3     Whale  Oil  Soap 1  pound 

Water  25  gallons 

No.  4     Kerosene    12  gallons 

Whale  Oil  Soap 4  pounds 

Water 100  gallons 

No.  5     Pyrethrum  Powder _ 1  pound 

Water  25  gallons 

As  has  been  previously  stated,  the  season  had  advanced  so  far 
that  the  results  from  the  different  sprays  were  not  very  conclusive, 
but  the  kerosene  emulsion  and  the  emulsion  and  whale  oil  soap  gave 
the  best  results.  The  Paris  Green  also  gave  good  results,  but  the 
pyrethrum  powder  was  a  total  failure. 

A  few  Zebra  Caterpillars  (Mamestra  picta)  were  found  in  a  num- 
ber of  fields  but  they  did  very  little  damage.  The  Red  Spider  also 
was  more  or  less  abundant  in  the  fields  and  did  some  damage,  espe- 
cially on  the  plants  at  the  ends  of  the  rows  or  in  portions  of  the  fields 
where  the  dust  settled.  If  this  insect  is  troublesome  dust  with  flowers 
of  sulphur  on  the  affected  areas.  That  is  best  done  in  the  early  morn- 
ing when  the  dew  is  on  the  plants. 


Bulletin  208.  THE  late  BLIGHT  OF  CELERY.  115 


ACKNOWLEDGMENTS. 

It  is  a  duty  and  a  pleasure  to  here  express  the  writer's  appreciation 
of  the  hearty  co-operation  given  by  the  Golden  West  Celery  and  Pro- 
duce Company,  the  California  Vegetable  Union,  and  the  Orange  Coun- 
ty Celery  Growers'  Association  for  this  work  and  for  the  money  sup- 
plied by  the  above,  which  made  the  invstigation  possible.  Acknowl- 
edgment is  here  given  to  Dr.  J.  E.  Coit,  Professor  H.  J.  Quayle  and 
Mr.  C.  N.  Jensen,  all  of  the  University  of  California  Experiment  Sta- 
tion, for  their  valued  assistance.  The  writer  also  wishes  to  express  his 
appreciation  of  the  cordial  co-operation  and  assistance  rendered  by 
Mr.  Harry  Woodington,  Superintendent  of  the  Golden  West  Celery 
and  Produce  Company 's  ranch  at  Smeltzer.  The  photographs,  except- 
ing figures  5  and  6  which  were  taken  by  Mr.  C.  N.  Jensen,  were  taken 
by  Mr.  N.  D.  Ingham  of  the  University  of  California  Experiment 
Station. 


STATION   PUBLICATIONS   AVAILABLE    FOR   DISTRIBUTION. 


REPORTS. 


1896. 


1902. 
1903. 
1904. 


Report  of  the  Viticultural  Work  during  the  seasons  1887-93,   with  data  regarding  the 

Vintages  of  1894-95. 
Resistant  Vines,  their  Selection,   Adaptation,   and  Grafting.      Appendix  to  Viticultural 

Report  for  1896. 
Report  of  the  Agricultural  Experiment  Station  for  1898-1901. 
Report  of  the  Agricultural  Experiment  Station  for   1901-03. 
Twenty-second  Report  of  the  Agricultural  Experiment   Station   for   1903-04. 


BULLETINS. 


Reprint. 

No.  128. 

133. 

140. 

142. 
147. 
149. 
151. 
152. 
153. 
154. 
159. 

161. 
162. 

165. 

167. 

168. 

169. 

170. 
171. 

172. 

174. 
176. 

177. 

178. 
179. 

180. 
181. 


Endurance    of    Drought    in    Soils 

of   the   Arid   Region. 
Nature,   Value   and   Utilization  of 

Alkali  Lands,   and  Tolerance  of 

Alkali.      (Revised   and   Reprint, 

1905.) 
Tolerance    of    Alkali    by    Various 

Cultures. 
Lands    of   the    Colorado    Delta    in 

Salton   Basin,    and   Supplement. 
Grasshoppers    in    California. 
Culture  Work  of  the  Sub-stations. 
California   Sugar  Industry. 
Arsenical   Insecticides. 
Fumigation  Dosage. 
Spraying  with  Distillates. 
Sulfur  Sprays  for  Red   Spider. 
Contribution     to     the      Study     of 

Fermentation. 
Tuberculosis  in  Fowls.    (Reprint.) 
Commercial   Fertilizers.     (Dec.    1, 

1904.) 

Asparagus  and  Asparagus  Rust 
in  California. 

Manufacture  of  Dry  Wines  in 
Hot  Countries. 

Observations  on  Some  Vine  Dis- 
eases in   Sonoma  County. 

Tolerance  of  the  Sugar  Beet  for 
Alkali. 

Studies    in    Grasshopper    Control. 

Commercial  Fertilizers.  (June  30, 
1905.) 

Further  Experience  in  Asparagus 

Rust  Control. 
A    New   Wine-cooling    Machine. 
Sugar   Beets  in   the   San  Joaquin 

Valley. 
A    New    Method    of    Making    Dry 

Red  Wine. 
Mosquito  Control. 
Commercial     Fertilizers.        (June, 

1906.) 

Resistant  Vineyards. 

The   Selection   of    Seed-Wheat. 


182.  Analysis     of      Paris     Green     and 

Lead  Arsenic.  Proposed  In- 
secticide  Law. 

183.  The   California   Tussock-moth. 

184.  Report    of    the    Plant    Pathologist 

to  July  1,   1906. 

185.  Report     of      Progress     iri     Cereal 

Investigations. 

186.  The   Oidium  of  the  Vine. 

187.  Commercial     Fertilizers.        (Janu- 

ary,   1907.) 

188.  Lining  of  Ditches  and  Reservoirs 

to  Prevent  Seepage  and  Losses. 

189.  Commercial     Fertilizers.        (June, 

1907.) 

190.  The  Brown  Rot  of  the  Lemon. 

191.  California   Peach   Blight. 

192.  Insects   Injurious  to   the  Vine   in 

California. 

193.  The   Best   Wine   Grapes   for   Cali- 

fornia ;  Pruning  Young  Vines ; 
Pruning   the    Sultanina. 

194.  Commercial      Fertilizers.        (Dec, 

1907.) 

195.  The  California  Grape  Root-worm. 

197.  Grape  Culture  in  California;   Im- 

proved Methods  of  Wine- 
Making;  Yeast  from  California 
Grapes. 

198.  The  Grape  Leaf-Hopper. 

199.  Bovine  Tuberculosis. 

200.  Gum  Diseases  of  Citrus  Trees  in 

California. 

201.  Commercial     Fertilizers.       (June, 

1908.) 

202.  Commercial  Fertilizers.      (Decem- 

ber,   1908.) 

203.  Report    of    the    Plant    Pathologist 

to  July    1,    1909. 

204.  The  Dairy  Cow's  Record  and  the 

Stable. 

205.  Commercial    Fertilizers.      (Decem- 

ber,  1909.) 

206.  Commercial      Fertilizers.        (June, 

1910.) 

207.  The  Control  of  the  Argentine  Ant. 


CIRCULARS. 


No.      1.      Texas  Fever. 
3.      Hog  Cholera. 
5.      Contagious  Abortion  in  Cows. 
7.      Remedies  for  Insects. 
9.      Asparagus  Rust. 

10.  Reading  Course  in  Economic  En- 

tomology.    (Revision.) 

11.  Fumigation  Practice. 

12.  Silk  Culture. 

15.      Recent    Problems    in    Agriculture. 

What     a     University     Farm     is 

For. 
17.     Why       Agriculture       Should       be 

Taught    in    the    Public    Schools. 
19.      Disinfection   of   Stables. 

29.  Preliminary    Announcement    Con- 

cerning Instruction  in  Prac- 
tical Agriculture  upon  the 
University  Farm,  Davisville, 
Cal. 

30.  White  Fly  in   California. 

32.  White   Fly   Eradication. 

33.  Packing   Prunes   in   Cans.      Cane 

Sugar  vs.  Beet  Sugar. 
35.      Southern    California    Pathological 
Laboratory    and    Citrus    Experi- 
ment Station. 


36.  Analyses    of    Fertilizers    for    Con- 

sumers. 

37.  Announcement  of  Farmers'   Short 

Courses  for  1908. 
39.      Instruction   in   Practical   Agricul- 
ture at  the  University  Farm. 

46.  Suggestions  for  Garden  Work   in 

California  Schools. 

47.  Agriculture  in  the   High   Schools. 

48.  Butter  Scoring  Contest,   1909. 

49.  Insecticides. 

50.  Fumigation  Scheduling. 

51.  University  Farm  School. 

52.  Information     for     Students 

cerning    the    College    of 
culture. 

53.  Announcement  of  Farmers'   Short 

Courses  for  1910. 

54.  Some     Creamery     Problems     and 

Tests. 

55.  Farmers'    Institutes    and    Univer- 

sity   Extension    in    Agriculture. 
57.      Announcement  of  Farmers'   Short 
Courses  in  Animal  Industry  and 
Veterinary  Science. 


Con- 
Agri- 


